Yep, you've hit it on the head: the fashion world heavily depends on hyperspecific brands. A parent company may own an immense number of outlet identities that aim to cater to a specific submarket. Hot Topic is a good parent company for ThinkGeek because their model is already built around faddish, meme-driven trends (as you said), but the two target audiences have little enough overlap that this will be a substantial diversification to their marketing reach.